Re: [PATCH v7 04/10] counter: 104-quad-8: Add Generic Counter interface support

[Jonathan Cameron]

On Thu, 21 Jun 2018 17:07:42 -0400
William Breathitt Gray <vilhelm.gray@xxxxxxxxx> wrote:

> This patch adds support for the Generic Counter interface to the
> 104-QUAD-8 driver. The existing 104-QUAD-8 device interface should not
> be affected by this patch; all changes are intended as supplemental
> additions as perceived by the user.
> 
> Generic Counter Counts are created for the eight quadrature channel
> counts, as well as their respective quadrature A and B Signals (which
> are associated via respective Synapse structures) and respective index
> Signals.
> 
> The new Generic Counter interface sysfs attributes are intended to
> expose the same functionality and data available via the existing
> 104-QUAD-8 IIO device interface; the Generic Counter interface serves
> to provide the respective functionality and data in a standard way
> expected of counter devices.
> 
> Signed-off-by: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>

On comment inline that the license changes should have been a separate patch
as it doesn't have anything to do with the move or additional subsystem
registration.  However, I don't care 'that much' if everything else is fine.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>

> ---
>  MAINTAINERS                            |   4 +-
>  drivers/{iio => }/counter/104-quad-8.c | 782 ++++++++++++++++++++++++-
>  drivers/counter/Kconfig                |  21 +
>  drivers/counter/Makefile               |   2 +
>  drivers/iio/counter/Kconfig            |  17 -
>  drivers/iio/counter/Makefile           |   1 -
>  6 files changed, 784 insertions(+), 43 deletions(-)
>  rename drivers/{iio => }/counter/104-quad-8.c (44%)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index c7fd36500635..4083523699f3 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -266,12 +266,12 @@ L:	linux-gpio@xxxxxxxxxxxxxxx
>  S:	Maintained
>  F:	drivers/gpio/gpio-104-idio-16.c
>  
> -ACCES 104-QUAD-8 IIO DRIVER
> +ACCES 104-QUAD-8 DRIVER
>  M:	William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
>  L:	linux-iio@xxxxxxxxxxxxxxx
>  S:	Maintained
>  F:	Documentation/ABI/testing/sysfs-bus-iio-counter-104-quad-8
> -F:	drivers/iio/counter/104-quad-8.c
> +F:	drivers/counter/104-quad-8.c
>  
>  ACCES PCI-IDIO-16 GPIO DRIVER
>  M:	William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
> diff --git a/drivers/iio/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
> similarity index 44%
> rename from drivers/iio/counter/104-quad-8.c
> rename to drivers/counter/104-quad-8.c
> index 92be8d0f7735..bbd1640f3a51 100644
> --- a/drivers/iio/counter/104-quad-8.c
> +++ b/drivers/counter/104-quad-8.c
> @@ -1,19 +1,12 @@
> +// SPDX-License-Identifier: GPL-2.0-only
>  /*
> - * IIO driver for the ACCES 104-QUAD-8
> + * Counter driver for the ACCES 104-QUAD-8
>   * Copyright (C) 2016 William Breathitt Gray
>   *
> - * This program is free software; you can redistribute it and/or modify
> - * it under the terms of the GNU General Public License, version 2, as
> - * published by the Free Software Foundation.
> - *
> - * This program is distributed in the hope that it will be useful, but
> - * WITHOUT ANY WARRANTY; without even the implied warranty of
> - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> - * General Public License for more details.
> - *

I know it's trivial, bu I would have preferred this as a precursor patch
rather than rolled in here.

Meh, doesn't really matter though but if you 'are' respinning for another
reason then it would be nice to clean up ;)

>   * This driver supports the ACCES 104-QUAD-8 and ACCES 104-QUAD-4.
>   */
>  #include <linux/bitops.h>
> +#include <linux/counter.h>
>  #include <linux/device.h>
>  #include <linux/errno.h>
>  #include <linux/iio/iio.h>
> @@ -37,6 +30,7 @@ MODULE_PARM_DESC(base, "ACCES 104-QUAD-8 base addresses");
>  
>  /**
>   * struct quad8_iio - IIO device private data structure
> + * @counter:		instance of the counter_device
>   * @preset:		array of preset values
>   * @count_mode:		array of count mode configurations
>   * @quadrature_mode:	array of quadrature mode configurations
> @@ -48,6 +42,7 @@ MODULE_PARM_DESC(base, "ACCES 104-QUAD-8 base addresses");
>   * @base:		base port address of the IIO device
>   */
>  struct quad8_iio {
> +	struct counter_device counter;
>  	unsigned int preset[QUAD8_NUM_COUNTERS];
>  	unsigned int count_mode[QUAD8_NUM_COUNTERS];
>  	unsigned int quadrature_mode[QUAD8_NUM_COUNTERS];
> @@ -91,6 +86,10 @@ struct quad8_iio {
>  #define QUAD8_RLD_CNTR_OUT 0x10
>  #define QUAD8_CHAN_OP_ENABLE_COUNTERS 0x00
>  #define QUAD8_CHAN_OP_RESET_COUNTERS 0x01
> +#define QUAD8_CMR_QUADRATURE_X1 0x08
> +#define QUAD8_CMR_QUADRATURE_X2 0x10
> +#define QUAD8_CMR_QUADRATURE_X4 0x18
> +
>  
>  static int quad8_read_raw(struct iio_dev *indio_dev,
>  	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
> @@ -346,13 +345,13 @@ static const char *const quad8_count_modes[] = {
>  };
>  
>  static int quad8_set_count_mode(struct iio_dev *indio_dev,
> -	const struct iio_chan_spec *chan, unsigned int count_mode)
> +	const struct iio_chan_spec *chan, unsigned int cnt_mode)
>  {
>  	struct quad8_iio *const priv = iio_priv(indio_dev);
> -	unsigned int mode_cfg = count_mode << 1;
> +	unsigned int mode_cfg = cnt_mode << 1;
>  	const int base_offset = priv->base + 2 * chan->channel + 1;
>  
> -	priv->count_mode[chan->channel] = count_mode;
> +	priv->count_mode[chan->channel] = cnt_mode;
>  
>  	/* Add quadrature mode configuration */
>  	if (priv->quadrature_mode[chan->channel])
> @@ -562,24 +561,746 @@ static const struct iio_chan_spec quad8_channels[] = {
>  	QUAD8_COUNT_CHAN(7), QUAD8_INDEX_CHAN(7)
>  };
>  
> +static int quad8_signal_read(struct counter_device *counter,
> +	struct counter_signal *signal, struct signal_read_value *val)
> +{
> +	const struct quad8_iio *const priv = counter->priv;
> +	unsigned int state;
> +	enum signal_level level;
> +
> +	/* Only Index signal levels can be read */
> +	if (signal->id < 16)
> +		return -EINVAL;
> +
> +	state = inb(priv->base + QUAD8_REG_INDEX_INPUT_LEVELS)
> +		& BIT(signal->id - 16);
> +
> +	level = (state) ? SIGNAL_LEVEL_HIGH : SIGNAL_LEVEL_LOW;
> +
> +	signal_read_value_set(val, SIGNAL_LEVEL, &level);
> +
> +	return 0;
> +}
> +
> +static int quad8_count_read(struct counter_device *counter,
> +	struct counter_count *count, struct count_read_value *val)
> +{
> +	const struct quad8_iio *const priv = counter->priv;
> +	const int base_offset = priv->base + 2 * count->id;
> +	unsigned int flags;
> +	unsigned int borrow;
> +	unsigned int carry;
> +	unsigned long position;
> +	int i;
> +
> +	flags = inb(base_offset + 1);
> +	borrow = flags & QUAD8_FLAG_BT;
> +	carry = !!(flags & QUAD8_FLAG_CT);
> +
> +	/* Borrow XOR Carry effectively doubles count range */
> +	position = (unsigned long)(borrow ^ carry) << 24;
> +
> +	/* Reset Byte Pointer; transfer Counter to Output Latch */
> +	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP | QUAD8_RLD_CNTR_OUT,
> +	     base_offset + 1);
> +
> +	for (i = 0; i < 3; i++)
> +		position |= (unsigned long)inb(base_offset) << (8 * i);
> +
> +	count_read_value_set(val, COUNT_POSITION, &position);
> +
> +	return 0;
> +}
> +
> +static int quad8_count_write(struct counter_device *counter,
> +	struct counter_count *count, struct count_write_value *val)
> +{
> +	const struct quad8_iio *const priv = counter->priv;
> +	const int base_offset = priv->base + 2 * count->id;
> +	int err;
> +	unsigned long position;
> +	int i;
> +
> +	err = count_write_value_get(&position, COUNT_POSITION, val);
> +	if (err)
> +		return err;
> +
> +	/* Only 24-bit values are supported */
> +	if (position > 0xFFFFFF)
> +		return -EINVAL;
> +
> +	/* Reset Byte Pointer */
> +	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP, base_offset + 1);
> +
> +	/* Counter can only be set via Preset Register */
> +	for (i = 0; i < 3; i++)
> +		outb(position >> (8 * i), base_offset);
> +
> +	/* Transfer Preset Register to Counter */
> +	outb(QUAD8_CTR_RLD | QUAD8_RLD_PRESET_CNTR, base_offset + 1);
> +
> +	/* Reset Byte Pointer */
> +	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP, base_offset + 1);
> +
> +	/* Set Preset Register back to original value */
> +	position = priv->preset[count->id];
> +	for (i = 0; i < 3; i++)
> +		outb(position >> (8 * i), base_offset);
> +
> +	/* Reset Borrow, Carry, Compare, and Sign flags */
> +	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_FLAGS, base_offset + 1);
> +	/* Reset Error flag */
> +	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_E, base_offset + 1);
> +
> +	return 0;
> +}
> +
> +enum quad8_count_function {
> +	QUAD8_COUNT_FUNCTION_PULSE_DIRECTION = 0,
> +	QUAD8_COUNT_FUNCTION_QUADRATURE_X1,
> +	QUAD8_COUNT_FUNCTION_QUADRATURE_X2,
> +	QUAD8_COUNT_FUNCTION_QUADRATURE_X4
> +};
> +
> +static enum count_function quad8_count_functions_list[] = {
> +	[QUAD8_COUNT_FUNCTION_PULSE_DIRECTION] = COUNT_FUNCTION_PULSE_DIRECTION,
> +	[QUAD8_COUNT_FUNCTION_QUADRATURE_X1] = COUNT_FUNCTION_QUADRATURE_X1_A,
> +	[QUAD8_COUNT_FUNCTION_QUADRATURE_X2] = COUNT_FUNCTION_QUADRATURE_X2_A,
> +	[QUAD8_COUNT_FUNCTION_QUADRATURE_X4] = COUNT_FUNCTION_QUADRATURE_X4
> +};
> +
> +static int quad8_function_get(struct counter_device *counter,
> +	struct counter_count *count, size_t *function)
> +{
> +	const struct quad8_iio *const priv = counter->priv;
> +	const int id = count->id;
> +	const unsigned int quadrature_mode = priv->quadrature_mode[id];
> +	const unsigned int scale = priv->quadrature_scale[id];
> +
> +	if (quadrature_mode)
> +		switch (scale) {
> +		case 0:
> +			*function = QUAD8_COUNT_FUNCTION_QUADRATURE_X1;
> +			break;
> +		case 1:
> +			*function = QUAD8_COUNT_FUNCTION_QUADRATURE_X2;
> +			break;
> +		case 2:
> +			*function = QUAD8_COUNT_FUNCTION_QUADRATURE_X4;
> +			break;
> +		}
> +	else
> +		*function = QUAD8_COUNT_FUNCTION_PULSE_DIRECTION;
> +
> +	return 0;
> +}
> +
> +static int quad8_function_set(struct counter_device *counter,
> +	struct counter_count *count, size_t function)
> +{
> +	struct quad8_iio *const priv = counter->priv;
> +	const int id = count->id;
> +	unsigned int *const quadrature_mode = priv->quadrature_mode + id;
> +	unsigned int *const scale = priv->quadrature_scale + id;
> +	unsigned int mode_cfg = priv->count_mode[id] << 1;
> +	unsigned int *const synchronous_mode = priv->synchronous_mode + id;
> +	const unsigned int idr_cfg = priv->index_polarity[id] << 1;
> +	const int base_offset = priv->base + 2 * id + 1;
> +
> +	if (function == QUAD8_COUNT_FUNCTION_PULSE_DIRECTION) {
> +		*quadrature_mode = 0;
> +
> +		/* Quadrature scaling only available in quadrature mode */
> +		*scale = 0;
> +
> +		/* Synchronous function not supported in non-quadrature mode */
> +		if (*synchronous_mode) {
> +			*synchronous_mode = 0;
> +			/* Disable synchronous function mode */
> +			outb(QUAD8_CTR_IDR | idr_cfg, base_offset);
> +		}
> +	} else {
> +		*quadrature_mode = 1;
> +
> +		switch (function) {
> +		case QUAD8_COUNT_FUNCTION_QUADRATURE_X1:
> +			*scale = 0;
> +			mode_cfg |= QUAD8_CMR_QUADRATURE_X1;
> +			break;
> +		case QUAD8_COUNT_FUNCTION_QUADRATURE_X2:
> +			*scale = 1;
> +			mode_cfg |= QUAD8_CMR_QUADRATURE_X2;
> +			break;
> +		case QUAD8_COUNT_FUNCTION_QUADRATURE_X4:
> +			*scale = 2;
> +			mode_cfg |= QUAD8_CMR_QUADRATURE_X4;
> +			break;
> +		}
> +	}
> +
> +	/* Load mode configuration to Counter Mode Register */
> +	outb(QUAD8_CTR_CMR | mode_cfg, base_offset);
> +
> +	return 0;
> +}
> +
> +static void quad8_direction_get(struct counter_device *counter,
> +	struct counter_count *count, enum count_direction *direction)
> +{
> +	const struct quad8_iio *const priv = counter->priv;
> +	unsigned int ud_flag;
> +	const unsigned int flag_addr = priv->base + 2 * count->id + 1;
> +
> +	/* U/D flag: nonzero = up, zero = down */
> +	ud_flag = inb(flag_addr) & QUAD8_FLAG_UD;
> +
> +	*direction = (ud_flag) ? COUNT_DIRECTION_FORWARD :
> +		COUNT_DIRECTION_BACKWARD;
> +}
> +
> +enum quad8_synapse_action {
> +	QUAD8_SYNAPSE_ACTION_NONE = 0,
> +	QUAD8_SYNAPSE_ACTION_RISING_EDGE,
> +	QUAD8_SYNAPSE_ACTION_FALLING_EDGE,
> +	QUAD8_SYNAPSE_ACTION_BOTH_EDGES
> +};
> +
> +static enum synapse_action quad8_index_actions_list[] = {
> +	[QUAD8_SYNAPSE_ACTION_NONE] = SYNAPSE_ACTION_NONE,
> +	[QUAD8_SYNAPSE_ACTION_RISING_EDGE] = SYNAPSE_ACTION_RISING_EDGE
> +};
> +
> +static enum synapse_action quad8_synapse_actions_list[] = {
> +	[QUAD8_SYNAPSE_ACTION_NONE] = SYNAPSE_ACTION_NONE,
> +	[QUAD8_SYNAPSE_ACTION_RISING_EDGE] = SYNAPSE_ACTION_RISING_EDGE,
> +	[QUAD8_SYNAPSE_ACTION_FALLING_EDGE] = SYNAPSE_ACTION_FALLING_EDGE,
> +	[QUAD8_SYNAPSE_ACTION_BOTH_EDGES] = SYNAPSE_ACTION_BOTH_EDGES
> +};
> +
> +static int quad8_action_get(struct counter_device *counter,
> +	struct counter_count *count, struct counter_synapse *synapse,
> +	size_t *action)
> +{
> +	struct quad8_iio *const priv = counter->priv;
> +	int err;
> +	size_t function = 0;
> +	const size_t signal_a_id = count->synapses[0].signal->id;
> +	enum count_direction direction;
> +
> +	/* Handle Index signals */
> +	if (synapse->signal->id >= 16) {
> +		if (priv->preset_enable[count->id])
> +			*action = QUAD8_SYNAPSE_ACTION_RISING_EDGE;
> +		else
> +			*action = QUAD8_SYNAPSE_ACTION_NONE;
> +
> +		return 0;
> +	}
> +
> +	err = quad8_function_get(counter, count, &function);
> +	if (err)
> +		return err;
> +
> +	/* Default action mode */
> +	*action = QUAD8_SYNAPSE_ACTION_NONE;
> +
> +	/* Determine action mode based on current count function mode */
> +	switch (function) {
> +	case QUAD8_COUNT_FUNCTION_PULSE_DIRECTION:
> +		if (synapse->signal->id == signal_a_id)
> +			*action = QUAD8_SYNAPSE_ACTION_RISING_EDGE;
> +		break;
> +	case QUAD8_COUNT_FUNCTION_QUADRATURE_X1:
> +		if (synapse->signal->id == signal_a_id) {
> +			quad8_direction_get(counter, count, &direction);
> +
> +			if (direction == COUNT_DIRECTION_FORWARD)
> +				*action = QUAD8_SYNAPSE_ACTION_RISING_EDGE;
> +			else
> +				*action = QUAD8_SYNAPSE_ACTION_FALLING_EDGE;
> +		}
> +		break;
> +	case QUAD8_COUNT_FUNCTION_QUADRATURE_X2:
> +		if (synapse->signal->id == signal_a_id)
> +			*action = QUAD8_SYNAPSE_ACTION_BOTH_EDGES;
> +		break;
> +	case QUAD8_COUNT_FUNCTION_QUADRATURE_X4:
> +		*action = QUAD8_SYNAPSE_ACTION_BOTH_EDGES;
> +		break;
> +	}
> +
> +	return 0;
> +}
> +
> +const struct counter_ops quad8_ops = {
> +	.signal_read = quad8_signal_read,
> +	.count_read = quad8_count_read,
> +	.count_write = quad8_count_write,
> +	.function_get = quad8_function_get,
> +	.function_set = quad8_function_set,
> +	.action_get = quad8_action_get
> +};
> +
> +static int quad8_index_polarity_get(struct counter_device *counter,
> +	struct counter_signal *signal, size_t *index_polarity)
> +{
> +	const struct quad8_iio *const priv = counter->priv;
> +	const size_t channel_id = signal->id - 16;
> +
> +	*index_polarity = priv->index_polarity[channel_id];
> +
> +	return 0;
> +}
> +
> +static int quad8_index_polarity_set(struct counter_device *counter,
> +	struct counter_signal *signal, size_t index_polarity)
> +{
> +	struct quad8_iio *const priv = counter->priv;
> +	const size_t channel_id = signal->id - 16;
> +	const unsigned int idr_cfg = priv->synchronous_mode[channel_id] |
> +		index_polarity << 1;
> +	const int base_offset = priv->base + 2 * channel_id + 1;
> +
> +	priv->index_polarity[channel_id] = index_polarity;
> +
> +	/* Load Index Control configuration to Index Control Register */
> +	outb(QUAD8_CTR_IDR | idr_cfg, base_offset);
> +
> +	return 0;
> +}
> +
> +static struct counter_signal_enum_ext quad8_index_pol_enum = {
> +	.items = quad8_index_polarity_modes,
> +	.num_items = ARRAY_SIZE(quad8_index_polarity_modes),
> +	.get = quad8_index_polarity_get,
> +	.set = quad8_index_polarity_set
> +};
> +
> +static int quad8_synchronous_mode_get(struct counter_device *counter,
> +	struct counter_signal *signal, size_t *synchronous_mode)
> +{
> +	const struct quad8_iio *const priv = counter->priv;
> +	const size_t channel_id = signal->id - 16;
> +
> +	*synchronous_mode = priv->synchronous_mode[channel_id];
> +
> +	return 0;
> +}
> +
> +static int quad8_synchronous_mode_set(struct counter_device *counter,
> +	struct counter_signal *signal, size_t synchronous_mode)
> +{
> +	struct quad8_iio *const priv = counter->priv;
> +	const size_t channel_id = signal->id - 16;
> +	const unsigned int idr_cfg = synchronous_mode |
> +		priv->index_polarity[channel_id] << 1;
> +	const int base_offset = priv->base + 2 * channel_id + 1;
> +
> +	/* Index function must be non-synchronous in non-quadrature mode */
> +	if (synchronous_mode && !priv->quadrature_mode[channel_id])
> +		return -EINVAL;
> +
> +	priv->synchronous_mode[channel_id] = synchronous_mode;
> +
> +	/* Load Index Control configuration to Index Control Register */
> +	outb(QUAD8_CTR_IDR | idr_cfg, base_offset);
> +
> +	return 0;
> +}
> +
> +static struct counter_signal_enum_ext quad8_syn_mode_enum = {
> +	.items = quad8_synchronous_modes,
> +	.num_items = ARRAY_SIZE(quad8_synchronous_modes),
> +	.get = quad8_synchronous_mode_get,
> +	.set = quad8_synchronous_mode_set
> +};
> +
> +static ssize_t quad8_count_floor_read(struct counter_device *counter,
> +	struct counter_count *count, void *private, char *buf)
> +{
> +	/* Only a floor of 0 is supported */
> +	return snprintf(buf, PAGE_SIZE, "0\n");
> +}
> +
> +static int quad8_count_mode_get(struct counter_device *counter,
> +	struct counter_count *count, size_t *cnt_mode)
> +{
> +	const struct quad8_iio *const priv = counter->priv;
> +
> +	/* Map 104-QUAD-8 count mode to Generic Counter count mode */
> +	switch (priv->count_mode[count->id]) {
> +	case 0:
> +		*cnt_mode = COUNT_MODE_NORMAL;
> +		break;
> +	case 1:
> +		*cnt_mode = COUNT_MODE_RANGE_LIMIT;
> +		break;
> +	case 2:
> +		*cnt_mode = COUNT_MODE_NON_RECYCLE;
> +		break;
> +	case 3:
> +		*cnt_mode = COUNT_MODE_MODULO_N;
> +		break;
> +	}
> +
> +	return 0;
> +}
> +
> +static int quad8_count_mode_set(struct counter_device *counter,
> +	struct counter_count *count, size_t cnt_mode)
> +{
> +	struct quad8_iio *const priv = counter->priv;
> +	unsigned int mode_cfg;
> +	const int base_offset = priv->base + 2 * count->id + 1;
> +
> +	/* Map Generic Counter count mode to 104-QUAD-8 count mode */
> +	switch (cnt_mode) {
> +	case COUNT_MODE_NORMAL:
> +		cnt_mode = 0;
> +		break;
> +	case COUNT_MODE_RANGE_LIMIT:
> +		cnt_mode = 1;
> +		break;
> +	case COUNT_MODE_NON_RECYCLE:
> +		cnt_mode = 2;
> +		break;
> +	case COUNT_MODE_MODULO_N:
> +		cnt_mode = 3;
> +		break;
> +	}
> +
> +	priv->count_mode[count->id] = cnt_mode;
> +
> +	/* Set count mode configuration value */
> +	mode_cfg = cnt_mode << 1;
> +
> +	/* Add quadrature mode configuration */
> +	if (priv->quadrature_mode[count->id])
> +		mode_cfg |= (priv->quadrature_scale[count->id] + 1) << 3;
> +
> +	/* Load mode configuration to Counter Mode Register */
> +	outb(QUAD8_CTR_CMR | mode_cfg, base_offset);
> +
> +	return 0;
> +}
> +
> +static struct counter_count_enum_ext quad8_cnt_mode_enum = {
> +	.items = count_mode_str,
> +	.num_items = ARRAY_SIZE(count_mode_str),
> +	.get = quad8_count_mode_get,
> +	.set = quad8_count_mode_set
> +};
> +
> +static ssize_t quad8_count_direction_read(struct counter_device *counter,
> +	struct counter_count *count, void *priv, char *buf)
> +{
> +	enum count_direction dir;
> +
> +	quad8_direction_get(counter, count, &dir);
> +
> +	return scnprintf(buf, PAGE_SIZE, "%s\n", count_direction_str[dir]);
> +}
> +
> +static ssize_t quad8_count_enable_read(struct counter_device *counter,
> +	struct counter_count *count, void *private, char *buf)
> +{
> +	const struct quad8_iio *const priv = counter->priv;
> +
> +	return scnprintf(buf, PAGE_SIZE, "%u\n", priv->ab_enable[count->id]);
> +}
> +
> +static ssize_t quad8_count_enable_write(struct counter_device *counter,
> +	struct counter_count *count, void *private, const char *buf, size_t len)
> +{
> +	struct quad8_iio *const priv = counter->priv;
> +	const int base_offset = priv->base + 2 * count->id;
> +	int err;
> +	bool ab_enable;
> +	unsigned int ior_cfg;
> +
> +	err = kstrtobool(buf, &ab_enable);
> +	if (err)
> +		return err;
> +
> +	priv->ab_enable[count->id] = ab_enable;
> +
> +	ior_cfg = ab_enable | priv->preset_enable[count->id] << 1;
> +
> +	/* Load I/O control configuration */
> +	outb(QUAD8_CTR_IOR | ior_cfg, base_offset + 1);
> +
> +	return len;
> +}
> +
> +static int quad8_error_noise_get(struct counter_device *counter,
> +	struct counter_count *count, size_t *noise_error)
> +{
> +	const struct quad8_iio *const priv = counter->priv;
> +	const int base_offset = priv->base + 2 * count->id + 1;
> +
> +	*noise_error = !!(inb(base_offset) & QUAD8_FLAG_E);
> +
> +	return 0;
> +}
> +
> +static struct counter_count_enum_ext quad8_error_noise_enum = {
> +	.items = quad8_noise_error_states,
> +	.num_items = ARRAY_SIZE(quad8_noise_error_states),
> +	.get = quad8_error_noise_get
> +};
> +
> +static ssize_t quad8_count_preset_read(struct counter_device *counter,
> +	struct counter_count *count, void *private, char *buf)
> +{
> +	const struct quad8_iio *const priv = counter->priv;
> +
> +	return snprintf(buf, PAGE_SIZE, "%u\n", priv->preset[count->id]);
> +}
> +
> +static ssize_t quad8_count_preset_write(struct counter_device *counter,
> +	struct counter_count *count, void *private, const char *buf, size_t len)
> +{
> +	struct quad8_iio *const priv = counter->priv;
> +	const int base_offset = priv->base + 2 * count->id;
> +	unsigned int preset;
> +	int ret;
> +	int i;
> +
> +	ret = kstrtouint(buf, 0, &preset);
> +	if (ret)
> +		return ret;
> +
> +	/* Only 24-bit values are supported */
> +	if (preset > 0xFFFFFF)
> +		return -EINVAL;
> +
> +	priv->preset[count->id] = preset;
> +
> +	/* Reset Byte Pointer */
> +	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP, base_offset + 1);
> +
> +	/* Set Preset Register */
> +	for (i = 0; i < 3; i++)
> +		outb(preset >> (8 * i), base_offset);
> +
> +	return len;
> +}
> +
> +static ssize_t quad8_count_ceiling_read(struct counter_device *counter,
> +	struct counter_count *count, void *private, char *buf)
> +{
> +	const struct quad8_iio *const priv = counter->priv;
> +
> +	/* Range Limit and Modulo-N count modes use preset value as ceiling */
> +	switch (priv->count_mode[count->id]) {
> +	case 1:
> +	case 3:
> +		return quad8_count_preset_read(counter, count, private, buf);
> +	}
> +
> +	/* By default 0x1FFFFFF (25 bits unsigned) is maximum count */
> +	return snprintf(buf, PAGE_SIZE, "33554431\n");
> +}
> +
> +static ssize_t quad8_count_ceiling_write(struct counter_device *counter,
> +	struct counter_count *count, void *private, const char *buf, size_t len)
> +{
> +	struct quad8_iio *const priv = counter->priv;
> +
> +	/* Range Limit and Modulo-N count modes use preset value as ceiling */
> +	switch (priv->count_mode[count->id]) {
> +	case 1:
> +	case 3:
> +		return quad8_count_preset_write(counter, count, private, buf,
> +						len);
> +	}
> +
> +	return len;
> +}
> +
> +static ssize_t quad8_count_preset_enable_read(struct counter_device *counter,
> +	struct counter_count *count, void *private, char *buf)
> +{
> +	const struct quad8_iio *const priv = counter->priv;
> +
> +	return snprintf(buf, PAGE_SIZE, "%u\n",
> +		!priv->preset_enable[count->id]);
> +}
> +
> +static ssize_t quad8_count_preset_enable_write(struct counter_device *counter,
> +	struct counter_count *count, void *private, const char *buf, size_t len)
> +{
> +	struct quad8_iio *const priv = counter->priv;
> +	const int base_offset = priv->base + 2 * count->id + 1;
> +	bool preset_enable;
> +	int ret;
> +	unsigned int ior_cfg;
> +
> +	ret = kstrtobool(buf, &preset_enable);
> +	if (ret)
> +		return ret;
> +
> +	/* Preset enable is active low in Input/Output Control register */
> +	preset_enable = !preset_enable;
> +
> +	priv->preset_enable[count->id] = preset_enable;
> +
> +	ior_cfg = priv->ab_enable[count->id] | (unsigned int)preset_enable << 1;
> +
> +	/* Load I/O control configuration to Input / Output Control Register */
> +	outb(QUAD8_CTR_IOR | ior_cfg, base_offset);
> +
> +	return len;
> +}
> +
> +static const struct counter_signal_ext quad8_index_ext[] = {
> +	COUNTER_SIGNAL_ENUM("index_polarity", &quad8_index_pol_enum),
> +	COUNTER_SIGNAL_ENUM_AVAILABLE("index_polarity",	&quad8_index_pol_enum),
> +	COUNTER_SIGNAL_ENUM("synchronous_mode", &quad8_syn_mode_enum),
> +	COUNTER_SIGNAL_ENUM_AVAILABLE("synchronous_mode", &quad8_syn_mode_enum)
> +};
> +
> +#define	QUAD8_QUAD_SIGNAL(_id, _name) {	\
> +	.id = (_id),			\
> +	.name = (_name)			\
> +}
> +
> +#define	QUAD8_INDEX_SIGNAL(_id, _name) {	\
> +	.id = (_id),				\
> +	.name = (_name),			\
> +	.ext = quad8_index_ext,			\
> +	.num_ext = ARRAY_SIZE(quad8_index_ext)	\
> +}
> +
> +static struct counter_signal quad8_signals[] = {
> +	QUAD8_QUAD_SIGNAL(0, "Channel 1 Quadrature A"),
> +	QUAD8_QUAD_SIGNAL(1, "Channel 1 Quadrature B"),
> +	QUAD8_QUAD_SIGNAL(2, "Channel 2 Quadrature A"),
> +	QUAD8_QUAD_SIGNAL(3, "Channel 2 Quadrature B"),
> +	QUAD8_QUAD_SIGNAL(4, "Channel 3 Quadrature A"),
> +	QUAD8_QUAD_SIGNAL(5, "Channel 3 Quadrature B"),
> +	QUAD8_QUAD_SIGNAL(6, "Channel 4 Quadrature A"),
> +	QUAD8_QUAD_SIGNAL(7, "Channel 4 Quadrature B"),
> +	QUAD8_QUAD_SIGNAL(8, "Channel 5 Quadrature A"),
> +	QUAD8_QUAD_SIGNAL(9, "Channel 5 Quadrature B"),
> +	QUAD8_QUAD_SIGNAL(10, "Channel 6 Quadrature A"),
> +	QUAD8_QUAD_SIGNAL(11, "Channel 6 Quadrature B"),
> +	QUAD8_QUAD_SIGNAL(12, "Channel 7 Quadrature A"),
> +	QUAD8_QUAD_SIGNAL(13, "Channel 7 Quadrature B"),
> +	QUAD8_QUAD_SIGNAL(14, "Channel 8 Quadrature A"),
> +	QUAD8_QUAD_SIGNAL(15, "Channel 8 Quadrature B"),
> +	QUAD8_INDEX_SIGNAL(16, "Channel 1 Index"),
> +	QUAD8_INDEX_SIGNAL(17, "Channel 2 Index"),
> +	QUAD8_INDEX_SIGNAL(18, "Channel 3 Index"),
> +	QUAD8_INDEX_SIGNAL(19, "Channel 4 Index"),
> +	QUAD8_INDEX_SIGNAL(20, "Channel 5 Index"),
> +	QUAD8_INDEX_SIGNAL(21, "Channel 6 Index"),
> +	QUAD8_INDEX_SIGNAL(22, "Channel 7 Index"),
> +	QUAD8_INDEX_SIGNAL(23, "Channel 8 Index")
> +};
> +
> +#define QUAD8_COUNT_SYNAPSES(_id) {					\
> +	{								\
> +		.actions_list = quad8_synapse_actions_list,		\
> +		.num_actions = ARRAY_SIZE(quad8_synapse_actions_list),	\
> +		.signal = quad8_signals + 2 * (_id)			\
> +	},								\
> +	{								\
> +		.actions_list = quad8_synapse_actions_list,		\
> +		.num_actions = ARRAY_SIZE(quad8_synapse_actions_list),	\
> +		.signal = quad8_signals + 2 * (_id) + 1			\
> +	},								\
> +	{								\
> +		.actions_list = quad8_index_actions_list,		\
> +		.num_actions = ARRAY_SIZE(quad8_index_actions_list),	\
> +		.signal = quad8_signals + 2 * (_id) + 16		\
> +	}								\
> +}
> +
> +static struct counter_synapse quad8_count_synapses[][3] = {
> +	QUAD8_COUNT_SYNAPSES(0), QUAD8_COUNT_SYNAPSES(1),
> +	QUAD8_COUNT_SYNAPSES(2), QUAD8_COUNT_SYNAPSES(3),
> +	QUAD8_COUNT_SYNAPSES(4), QUAD8_COUNT_SYNAPSES(5),
> +	QUAD8_COUNT_SYNAPSES(6), QUAD8_COUNT_SYNAPSES(7)
> +};
> +
> +static const struct counter_count_ext quad8_count_ext[] = {
> +	{
> +		.name = "ceiling",
> +		.read = quad8_count_ceiling_read,
> +		.write = quad8_count_ceiling_write
> +	},
> +	{
> +		.name = "floor",
> +		.read = quad8_count_floor_read
> +	},
> +	COUNTER_COUNT_ENUM("count_mode", &quad8_cnt_mode_enum),
> +	COUNTER_COUNT_ENUM_AVAILABLE("count_mode", &quad8_cnt_mode_enum),
> +	{
> +		.name = "direction",
> +		.read = quad8_count_direction_read
> +	},
> +	{
> +		.name = "enable",
> +		.read = quad8_count_enable_read,
> +		.write = quad8_count_enable_write
> +	},
> +	COUNTER_COUNT_ENUM("error_noise", &quad8_error_noise_enum),
> +	COUNTER_COUNT_ENUM_AVAILABLE("error_noise", &quad8_error_noise_enum),
> +	{
> +		.name = "preset",
> +		.read = quad8_count_preset_read,
> +		.write = quad8_count_preset_write
> +	},
> +	{
> +		.name = "preset_enable",
> +		.read = quad8_count_preset_enable_read,
> +		.write = quad8_count_preset_enable_write
> +	}
> +};
> +
> +#define QUAD8_COUNT(_id, _cntname) {					\
> +	.id = (_id),							\
> +	.name = (_cntname),						\
> +	.functions_list = quad8_count_functions_list,			\
> +	.num_functions = ARRAY_SIZE(quad8_count_functions_list),	\
> +	.synapses = quad8_count_synapses[(_id)],			\
> +	.num_synapses =	2,						\
> +	.ext = quad8_count_ext,						\
> +	.num_ext = ARRAY_SIZE(quad8_count_ext)				\
> +}
> +
> +static struct counter_count quad8_counts[] = {
> +	QUAD8_COUNT(0, "Channel 1 Count"),
> +	QUAD8_COUNT(1, "Channel 2 Count"),
> +	QUAD8_COUNT(2, "Channel 3 Count"),
> +	QUAD8_COUNT(3, "Channel 4 Count"),
> +	QUAD8_COUNT(4, "Channel 5 Count"),
> +	QUAD8_COUNT(5, "Channel 6 Count"),
> +	QUAD8_COUNT(6, "Channel 7 Count"),
> +	QUAD8_COUNT(7, "Channel 8 Count")
> +};
> +
>  static int quad8_probe(struct device *dev, unsigned int id)
>  {
>  	struct iio_dev *indio_dev;
> -	struct quad8_iio *priv;
> +	struct quad8_iio *quad8iio;
>  	int i, j;
>  	unsigned int base_offset;
> +	int err;
>  
> -	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
> -	if (!indio_dev)
> -		return -ENOMEM;
> -
> -	if (!devm_request_region(dev, base[id], QUAD8_EXTENT,
> -		dev_name(dev))) {
> +	if (!devm_request_region(dev, base[id], QUAD8_EXTENT, dev_name(dev))) {
>  		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
>  			base[id], base[id] + QUAD8_EXTENT);
>  		return -EBUSY;
>  	}
>  
> +	/* Allocate IIO device; this also allocates driver data structure */
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*quad8iio));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	/* Initialize IIO device */
>  	indio_dev->info = &quad8_info;
>  	indio_dev->modes = INDIO_DIRECT_MODE;
>  	indio_dev->num_channels = ARRAY_SIZE(quad8_channels);
> @@ -587,8 +1308,17 @@ static int quad8_probe(struct device *dev, unsigned int id)
>  	indio_dev->name = dev_name(dev);
>  	indio_dev->dev.parent = dev;
>  
> -	priv = iio_priv(indio_dev);
> -	priv->base = base[id];
> +	/* Initialize Counter device and driver data */
> +	quad8iio = iio_priv(indio_dev);
> +	quad8iio->counter.name = dev_name(dev);
> +	quad8iio->counter.parent = dev;
> +	quad8iio->counter.ops = &quad8_ops;
> +	quad8iio->counter.counts = quad8_counts;
> +	quad8iio->counter.num_counts = ARRAY_SIZE(quad8_counts);
> +	quad8iio->counter.signals = quad8_signals;
> +	quad8iio->counter.num_signals = ARRAY_SIZE(quad8_signals);
> +	quad8iio->counter.priv = quad8iio;
> +	quad8iio->base = base[id];
>  
>  	/* Reset all counters and disable interrupt function */
>  	outb(QUAD8_CHAN_OP_RESET_COUNTERS, base[id] + QUAD8_REG_CHAN_OP);
> @@ -614,7 +1344,13 @@ static int quad8_probe(struct device *dev, unsigned int id)
>  	/* Enable all counters */
>  	outb(QUAD8_CHAN_OP_ENABLE_COUNTERS, base[id] + QUAD8_REG_CHAN_OP);
>  
> -	return devm_iio_device_register(dev, indio_dev);
> +	/* Register IIO device */
> +	err = devm_iio_device_register(dev, indio_dev);
> +	if (err)
> +		return err;
> +
> +	/* Register Counter device */
> +	return devm_counter_register(dev, &quad8iio->counter);
>  }
>  
>  static struct isa_driver quad8_driver = {
> diff --git a/drivers/counter/Kconfig b/drivers/counter/Kconfig
> index 65fa92abd5a4..7646f5df76f3 100644
> --- a/drivers/counter/Kconfig
> +++ b/drivers/counter/Kconfig
> @@ -16,3 +16,24 @@ menuconfig COUNTER
>  	  consumption. The Generic Counter interface enables drivers to support
>  	  and expose a common set of components and functionality present in
>  	  counter devices.
> +
> +if COUNTER
> +
> +config 104_QUAD_8
> +	tristate "ACCES 104-QUAD-8 driver"
> +	depends on PC104 && X86 && IIO
> +	select ISA_BUS_API
> +	help
> +	  Say yes here to build support for the ACCES 104-QUAD-8 quadrature
> +	  encoder counter/interface device family (104-QUAD-8, 104-QUAD-4).
> +
> +	  A counter's respective error flag may be cleared by performing a write
> +	  operation on the respective count value attribute. Although the
> +	  104-QUAD-8 counters have a 25-bit range, only the lower 24 bits may be
> +	  set, either directly or via the counter's preset attribute. Interrupts
> +	  are not supported by this driver.
> +
> +	  The base port addresses for the devices may be configured via the base
> +	  array module parameter.
> +
> +endif # COUNTER
> diff --git a/drivers/counter/Makefile b/drivers/counter/Makefile
> index ad1ba7109cdc..23a4f6263e45 100644
> --- a/drivers/counter/Makefile
> +++ b/drivers/counter/Makefile
> @@ -6,3 +6,5 @@
>  
>  obj-$(CONFIG_COUNTER) += counter.o
>  counter-y := generic-counter.o
> +
> +obj-$(CONFIG_104_QUAD_8)	+= 104-quad-8.o
> diff --git a/drivers/iio/counter/Kconfig b/drivers/iio/counter/Kconfig
> index bf1e559ad7cd..eeb358122cbe 100644
> --- a/drivers/iio/counter/Kconfig
> +++ b/drivers/iio/counter/Kconfig
> @@ -5,23 +5,6 @@
>  
>  menu "Counters"
>  
> -config 104_QUAD_8
> -	tristate "ACCES 104-QUAD-8 driver"
> -	depends on PC104 && X86
> -	select ISA_BUS_API
> -	help
> -	  Say yes here to build support for the ACCES 104-QUAD-8 quadrature
> -	  encoder counter/interface device family (104-QUAD-8, 104-QUAD-4).
> -
> -	  Performing a write to a counter's IIO_CHAN_INFO_RAW sets the counter and
> -	  also clears the counter's respective error flag. Although the counters
> -	  have a 25-bit range, only the lower 24 bits may be set, either directly
> -	  or via a counter's preset attribute. Interrupts are not supported by
> -	  this driver.
> -
> -	  The base port addresses for the devices may be configured via the base
> -	  array module parameter.
> -
>  config STM32_LPTIMER_CNT
>  	tristate "STM32 LP Timer encoder counter driver"
>  	depends on MFD_STM32_LPTIMER || COMPILE_TEST
> diff --git a/drivers/iio/counter/Makefile b/drivers/iio/counter/Makefile
> index 1b9a896eb488..93933ba49280 100644
> --- a/drivers/iio/counter/Makefile
> +++ b/drivers/iio/counter/Makefile
> @@ -4,5 +4,4 @@
>  
>  # When adding new entries keep the list in alphabetical order
>  
> -obj-$(CONFIG_104_QUAD_8)	+= 104-quad-8.o
>  obj-$(CONFIG_STM32_LPTIMER_CNT)	+= stm32-lptimer-cnt.o